Conventional solid-state lasers provide only a single beam of laser output at a given time, and conventional solid-state harmonic lasers provide only a single harmonic beam of laser output at a given time. An exemplary solid-state harmonic laser produces UV laser pulses of 8–10 W average power in a single beam at a repetition rate of about 1–100 kHz. To increase laser system throughput for a given laser micromachining operation, skilled practitioners have used laser systems with more than one laser head or a variety of beam-splitting techniques. These techniques have several disadvantages.
If two or more lasers are employed to increase system throughput by processing identical targets simultaneously with parallel processing operations, then the extra lasers require additional space for and multiply the cost of the laser system. Even when such lasers employ identical pumping sources, laser media, harmonic converters, and output coupling mirrors in an “identical” design, and additionally employ identical optical-path components and system control electronics, skilled persons will appreciate that it is difficult to match the laser output parameters, such as energy per pulse, beam shape or quality, and/or divergence angle or focused spot size, of each of the different laser beams due to variations in the quality of the components when they are new and due to variations in age-related deterioration of the components.
On the other hand, beam-splitting techniques, such as those employed to increase throughput in applications such as via drilling, require a higher-power laser beam to be generated from the laser so that the generated beam can be divided into the number of desired beams. Unfortunately, the highest practical available harmonic power is primarily limited by the risk of damage to the harmonic converter. Higher power capabilities also tend to decrease the reliability of the laser head, increase the damage risk to various optical components, and decrease the laser system lifetime.
Solid-state harmonic lasers and methods for employing such lasers that overcome these disadvantages are, therefore, desirable.